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Dr RCG ☆ 2011-02-04 05:51 (5619 d 19:45 ago) (edited on 2011-02-04 08:46) Posting: # 6552 Views: 4,988 |
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Dilution Integrity and Partial Volume paramters are performed in method valdiation. I want to know that: 1. Dilution Integrity (DI) is same as partial volume (PV). 2. Whether both the (DI and PV) parameters are two different experiments Can you tell me the difference between DI and PV & how it wil be use full in subject sample analysis. Edit: Category changed. [Ohlbe] |
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Ohlbe ★★★ France, 2011-02-04 09:57 (5619 d 15:38 ago) @ Dr RCG Posting: # 6553 Views: 4,155 |
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Dear Dr RCG, It is at the same time the same and different... - The aim of Dilution Integrity is to show whether if you have a sample with a concentration higher than the upper limit of quantification of your method (highest calibration sample), you can dilute it with blank plasma and get the correct result. To demonstrate this you will spike a QC sample at a high level of concentration, higher than your ULOQ, and analyse it after an appropriate dilution with blank plasma. - Partial Volume is particularly important in pre-clinical studies, where for some samples the volume of plasma you get is less than what you need for your analysis. It is less important in BE trials, where usually the volume of sample is sufficient. Let's imagine that you need 100 µl of plasma in your method, but for a given sample you only have 50 µl. You have two options: either dilute your sample with blank plasma, so that you still get 100 µl to process; or just process your 50 µl, leaving all other parameters unchanged. The first case is close to dilution integrity, except that you will have to demonstrate that it works also with a sample with a low concentration; I would not recommend the second option as you may get differences in recovery or matrix effects, but if you do it you need to demonstrate that it works. Regards Ohlbe — Regards Ohlbe |
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Dr RCG ☆ 2011-02-04 10:21 (5619 d 15:15 ago) @ Ohlbe Posting: # 6554 Views: 4,085 |
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Dear Ohlbe, Thanks for your quick response. DI issue is clear with me  . Regarding partial volume  , will discuss with team member and get back on same. Tks once againI have discussed with my team member. there are two things:
So can we say that DI and PV are same or Two different experiment since its way of sample preparation is different. Waiting for your valuable suggestions. Regards, DR RCG |
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Ohlbe ★★★ France, 2011-02-04 11:20 (5619 d 14:16 ago) @ Dr RCG Posting: # 6555 Views: 4,188 |
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Dear Dr RCG, ❝ 1. In DI processing volume is constant. e.g if processing volume is 500µl, then you will add 500µl to the sample - mix well and process only 500µl of it. Not necessarily. You can also directly take 250 µl + 250 µl into your extraction tube. ❝ since DI and PV has different way of sample preparation. ❝ so my point of view is that we should do different set of experiments for DI and PV Sample preparation may not be different. However the level of concentration can be different: dilution integrity will be done at a high level of concentration (higher than the ULOQ), but it would be better to do partial volume at a lower level of concentration (so that after dilution you get a concentration close to the LLOQ, or within a few times of the LLOQ. This will better reflect what happens in your study. ❝ and also mention in the method validation SOP. Yes. But depending on the type of samples you get to analyse, you may not need to do partial validation systematically. If you have to analyse samples from pre-clinical studies or from clinical studies in children, then it would certainly be a good idea to do it as you are likely to get some samples with insufficient volume. If you analyse samples from PK studies in human healthy subjects, unless you have to start from 1 ml of plasma it is usually not needed. Regards Ohlbe — Regards Ohlbe |
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Dr RCG ☆ 2011-02-05 05:55 (5618 d 19:40 ago) @ Ohlbe Posting: # 6561 Views: 4,128 |
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❝ ❝ since DI and PV has different way of sample preparation. ❝ ❝ so my point of view is that we should do different set of experiments for DI and PV ❝ ❝ Sample preparation may not be different. However the level of concentration can be different: dilution integrity will be done at a high level of concentration (higher than the ULOQ), but it would be better to do partial volume at a lower level of concentration (so that after dilution you get a concentration close to the LLOQ, or within a few times of the LLOQ. This will better reflect what happens in your study. ❝ ❝ ❝ and also mention in the method validation SOP. Dear Ohlbe, I still feel  that DI and PV should be mentioned separately in method validation SOP because the actual volume of sample is different in both the experiment. As PV can be done at any concentration including values below BLQ to ULOQ. DI can only be done if your unknown concentration is above ULOQ. This is what I understand clearly  . Please give your suggestion whether to separately mention both (DI & PV) the parameters in method validation SOP. |
Ing. Helmut Schütz